The UK Government released its official green car list in July 2007. The major surprise was that the number one green car was not the Toyota Prius or Honda Civic hybrids but the diesel engine Volkswagen Polo BlueMotion 1.4 TDI. The good news for current owners and prospective owners is that Polo BlueMotion is so green that it is the first conventional car to be made exempt from road tax.

The BlueMotion manages an amazing 74 miles per gallon and the CO2 emissions of the 1.4 TDI, at a meagre 99 g/km, fall into the much-sought ECO Band A.

Volkswagen are delighted to have earnt this accolade and the buzz surrounding this news has ensured that the Polo BlueMotion, which is not available in the UK until October, has already almost sold out.

The Volkswagen method for reducing emissions uses conventional technology such as lighter, low-friction tyres and a streamlined grill and the result of this technology is a car that has a top speed of 109 miles per hour but CO2 emissions of only 99 g/km. Finally, to shave off the final few grams of CO2 BlueMotion 1 drivers will have to do without air-conditioning (this is available only on the BlueMotion 2, which has slightly higher emissions of 104g/km, putting it in tax band B).

The arrival of the first tax-free cars coincides with the launch of a £10m government campaign to encourage motorists to buy greener cars. Branded “Act on CO2 funded by the Department for Transport (DfT), the campaign will include the launch of a new website that will enable drivers to search for the cars with the lowest emissions according to their particular needs.

The Vehicle Certification Agency’s website www.vca.gov.uk currently allows car buyers to search for emissions figures by make and model but it’s a laborious process and relies on motorists knowing the names of the makes and models they wish to compare.

“This is valuable extra information for consumers,” said a spokesman for the DfT last week. “It will make it much easier for them to take environmental considerations into account.”

The BlueMotion 1’s official emissions figure is 20g/km lower than the conventional 1.4 litre diesel Polo and 39g/km lower than the entry model 1.2 litre petrol.

Other car companies are also planning zero tax models. Smart plans to follow suit with its Fortwo diesel, available in the UK from early next year and which, at 88g/km of CO2, will have the lowest emissions of any new car – 16g lower than a petrol-electric Toyota Prius, the current car of choice for those keen to show off their environmental credentials.

With governments rewarding low emissions, environmentally friendly cars are here to stay, but what’s more surprising is that this is being driven by ultra-efficient common-rail diesel engines instead of the much trumpeted hybrid petrol/electric engines. With concept diesel hybrid engines being promoted, it seems that diesel is at the forefront of the “green revolution” and looks set to become the eco-warrior’s fuel of choice.